01 - Preheat the oven to 350°F. Grease and line an 8x8-inch baking pan with parchment paper, ensuring overhang for easy removal.
02 - In a large mixing bowl, whisk together melted butter, granulated sugar, and strawberry puree until thoroughly blended.
03 - Incorporate eggs and vanilla extract into the mixture, whisking until smooth and fully integrated.
04 - In a separate bowl, whisk together all-purpose flour, baking powder, and salt.
05 - Gently fold the dry ingredients into the wet mixture, mixing only until just combined to avoid over-mixing.
06 - Pour the batter into the prepared pan and smooth the surface evenly with a spatula.
07 - Bake for 22 to 25 minutes, or until the edges are set and a toothpick inserted into the center emerges with a few moist crumbs.
08 - Allow the baked slab to cool completely in the pan on a wire rack.
09 - Whisk powdered sugar with 2 to 3 tablespoons strawberry puree and lemon juice (if using) until smooth and pourable.
10 - Spread the glaze evenly over the cooled brownies, allow to set for 15 minutes, then cut into squares and serve.